If you turn off the "Sum" option and try to add two displacement vectors, each with a length of 18.0 meters, to produce an overall displacement of 30.0 meters to the right, you will see that it's not possible. The sum of two vectors, each with a magnitude of 18.0 meters, cannot result in a total displacement of 30.0 meters to the right.
From a physical perspective, this means that if a person walks 18.0 meters to the right and then 18.0 meters to the right again, their total displacement will be 36.0 meters to the right, not 30.0 meters as required.
Interpreting this in terms of instructions for a person walking from their home to a market, it would mean that the person would need to walk more than 30.0 meters to reach the market. The instructions would need to be adjusted to ensure they reach the market with a displacement of exactly 30.0 meters to the right.